and otherwise wait till you're in Shion's own bedroom, it is known that that savepoint actually does work and otherwise indeed use savestates until you're out of the Vector ship, even though it's not recommended to use savestates.

Well, there are a series of reasons to avoid using sstates "exclusively". First of all because it keeps whatever memory corruption, be it by emulation mistake or wrong cheat codes... really whatever cause. So the sstate has the potential to accumulate memory corruption to a breaking point.

Second, sstates should never be used to keep long term saves, this is far better kept on memcard. Among the reasons to have memcard saves being they will work with every emulator's versions or builds (sstates aren't grant to work in between versions or builds even).

So, why using sstates at all?

Simple answer, they are practical and actually the only way to save in between save points, or even inside a battle mode. Besides they are a bless if you have to emergency quit the gaming session.

Let's understand that sstates are a bless but they might be a curse if used the wrong way. This game is a prime example where one should use sstates a lot till getting out that problematic part, yet, even so, once possible do a memcard save by all means and continue doing so.

Be used to once and again to load from the memcard save and make a new clean sstate to grant possible memory corruptions are cleaned. Don't be shy using sstates, just remember they are useful in between save points. Do never pass by the opportunity to do a normal save.